Origen

In the Middle Ages office meant a duty that went with someone's position or employment. It goes back ultimately to Latin officium ‘performance of a task’, which in turn comes from the combined elements of opus ‘work’ (source of English opus in the early 19th century and of operation (Late Middle English)) and facere ‘to do’. The sense of ‘a place for business’ is recorded from the later Middle Ages. Someone officious (Late Middle English) was originally obliging or efficient in carrying out their office. The word developed its modern negative sense at the end of the 16th century.